Developmental expression of voltage-gated potassium (Kv)1 channels at the axon initial segment (AIS) and juxtapara (JXP)-AIS. (A-T) Triple immunostaining of ankyrin G (AnkG) (A, E, I, M, Q), contactin-associated protein (Caspr) (B, F, J, N, R) and Kv1.1 channels (C, G, K, O, S) (Caspr and Kv1.1 are merged in D, H, L, P, T) along the axon of motor neurons (MNs) labeled with the anti-Peripherin antibody (data not shown), from P1 to P14. Brackets indicate the Caspr+ domain (I-K, M-O, Q-S). (A'-T') Triple immunostaining of AnkG (A', E', I', M'), MBP (B', F', J', N') and Kv1.1 channels (C', G', K', O') (Caspr and MBP are merged in D', H', L', P') along the axon of MNs labeled with Peripherin (data not shown), from P3 to P14. Brackets indicate the MBP+ domain (E'-F', I'-K', M'-O'). Scale bar = 5 μm.